1. Field of the Invention
The present invention relates to a communication technique with a cartridge having a recording material held therein. More specifically the invention pertains to a technique of establishing communication with such a cartridge by wireless.
2. Description of the Related Art
Diverse recording apparatuses have been used widely; for example, recording apparatuses (printers) that eject inks on printing paper to print images, such as ink jet printers, and recording apparatuses that utilize toners to print images. Each cartridge mounted on such a printer contains a recording material like ink or toner and has a memory for storing data regarding the recording material or a sensor for detecting the presence or the absence of the recording material. The technique of such printers is disclosed, for example, in PATENT LAID-OPEN GAZETTE No. 2001-147146.
The cartridge is required to transmit the detection result of the sensor and the storage contents of the memory to and from the printer. Recently proposed techniques utilize wireless communication for such data transmission. The printer stops each cartridge in front of a coil functioning as an antenna and establishes communication with the cartridge by means of electromagnetic induction or another technique.
The communicable range of the cartridge is often restricted in wireless communication. The stop position of the cartridge is thus required to be specified with high accuracy. The wider communicable range does not require the cartridge to be positioned with high accuracy relative to the antenna for wireless communication. The output of wireless communication for this purpose is, however, generally rather restricted and has a narrow communicable range. Extension of the communication range is not at all practical, since it may cause interferences of adjoining printers and releases unnecessary radio waves.
The issue of the accuracy of positioning in wireless communication is discussed with a concrete example. In a printer with multiple ink cartridges mounted thereon, each cartridge has a communication module and the distance between adjoining cartridges is about 13 millimeters. The responsive range of each communication module to an antenna provided on the printer is smaller than this distance (for example, 8 millimeters). In the actual state, the allowable positioning accuracy of a carriage with the multiple cartridges is only 1 or 2 millimeters by taking into account the dimensional tolerance of the location of the antenna and the variation in communicable range. It is not easy to stop the carriage of a certain weight with the multiple ink cartridges mounted thereon relative to the antenna with such a high positioning accuracy. The insufficiency in positioning accuracy or in communicable range may cause plural communication modules of plural ink cartridges to enter the range of wireless communication simultaneously. This requires identification of the target of communication (anti-collision process).